DK Patent Publication No. 53516 or DK Published Application No. 146.023 discloses a method including blowing mould sand into a mould chamber using a tube, prior to the blowing-in operation having been introduced far into the mould chamber and during the blowing-in operation being pulled or pushed back gradually, so that the blowing-in occurs locally in the places where the mouth of the tube passes by.
In the process disclosed in this manner, the blowing-in operation is substantially directed more or less in a direction directly opposite to the direction in which the tube is being moved out of the mould chamber during the blowing-in operation. Admittedly, said publication mentions a single exception, viz. on page 5, first column, 3rd paragraph, referring to the possibility of imparting a helical movement to the sand when it leaves the mouthpiece. Even with such a helical movement, the sand will, however, substantially be blown in in a backward direction relative to the outwardly directed working movement of the blowing-in tube. For which reason the method is not well suited to the making of casting moulds or casting-mould parts in cases where patterns placed in the mould chamber comprise parts protruding transversely to the direction of movement of the blowing-in tube, there being a great risk of the formation of "shadow regions" on the sides of the protruding parts not being directly hit by the mould sand being blown in.
In the disclosed process, it will also be appreciated that the compaction of the mould sand is achieved solely by means of the force with which it is thrown against the walls of the mould chamber, or sand having been blown in previously during the blowing-in operation. Especially when making moulds or mould parts to be used for casting objects with a complex shape, this can result in the mould or mould part not achieving the requisite compactness throughout its volume.